Method of protecting wood through enhanced penetration of wood preservatives and a related solution

ABSTRACT

A method of protecting wood through enhanced penetration of wood preservatives includes providing a solution including (a) at least one amine oxide, (b) at least one organic wood preservative and (c) a buffering agent. The solution preferably has a pH of about 7 to 10. The solution is applied to the surface of the wood after which, with or without intervening storage, the materials are activated to effect enhanced penetration of the organic wood preservative into the wood. One may effect application at a solution temperature of about 30 to 75° C. and preferably about 50 to 60° C. to effect activation at a higher temperature and high relative humidity. In a preferred practice, the wood may be heated before and/or after application of the solution. The solution is also disclosed as a product.

CROSS REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. patent application Ser. No.11/135,770, filed May 24, 2005, and entitled “Method of Protecting WoodThrough Enhanced Penetration of Wood Preservatives and RelatedSolution,” now U.S. Pat. No. 7,655,281 which is herein incorporated byreference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an improved method of effectingenhanced penetration of wood preservatives into wood and, morespecifically, it relates to such a method which contains a bufferedcompound which facilitates enhanced penetration of wood preservativesinto the wood.

2. Description of the Prior Art

It has been known for many years to treat wood with materials which willprotect the wood from deterioration. Among such approaches have beensurface painting or the use of materials which will penetrate into thewood as by pressure impregnation or vacuum application. Among thematerials used are fungicides, insecticides, decay-resisting materials,stain-resisting materials, weather proofing materials and others. See,for example, U.S. Pat. Nos. 4,879,083; 4,950,685; 5,468,284; 5,763,338;5,833,741; 5,855,817; 5,972,266; 6,416,789 and 6,582,732.

In pressure and vacuum methods, the wood is treated with water orsolvents that carry preservatives. The pressure or vacuum methods causethe wood to pick up large amounts of these carriers and, as a result,require kiln drying or oven drying or long-term air drying to allow thewood to be useful. Such drying of pressure or vacuum-treated wood usingwater as a carrier can cause structural defects such as warping,cracking and checking.

It has been known to suggest the use of amine oxides in combination withother materials in wood preservatives. See, for example, U.S. Pat. Nos.6,274,199; 6,375,727; 6,448,279 and 6,527,981.

It has also been known to introduce into woods materials forfire-retardant properties. U.S. Pat. No. 6,811,731 discloses fireretardant protection achieved by treating green wood with aphosphate/borate.

It has also been known to suggest the combination of an amine oxide witha boron compound with the boron compound employed in a large enoughamount to function as a preservative in wood. See U.S. Pat. No.5,846,305 and United States Published Patent Application 20020065206,now U.S. Pat. No. 6,508,869.

In the use of known prior art systems which required pressureimpregnation or vacuum, capital investment for the equipment needed toachieve the desired pressure relationship influenced the economics ofintroduction of wood-preservative materials. Also, some prior artsystems employed volatile solvents which presented environmentallyundesirable conditions. In addition, such solvents added to the cost ofsuch procedures. An example of such undesirable materials are petroleumdistillates.

There remains, therefore, a very real and substantial need for animproved means of effectively achieving the desired level of penetrationin wood preservatives while having favorable economic aspects andavoiding risks to human health and environmentally undesirableconditions.

SUMMARY OF THE INVENTION

The present invention has met the hereinbefore described needs.

The method of the present invention permits enhanced penetration of woodpreservatives through the use of solutions having a buffered pH abovethe pH of the wood achieved through the use of a combination of an amineoxide and a buffering agent.

In a preferred practice of the method, a solution is created with atleast one amine oxide along with the wood preservative which is to beapplied to the wood and a buffering agent. This solution has a pH ofabout 5 to 12.4 and preferably about 7 to 10 and most preferably about 7to 8.5. It is applied to the surface of the wood. With or withoutintervening storage, activation results in the amine oxide and thebuffering agent in the solution combining to enhance penetration intothe wood of one or more wood preservatives. It is preferred that theapplication be at a solution temperature of about 30 to 75° C. and thatthe activation be at a higher temperature in a high relative humidityenvironment. The wood may also be heated before and/or after applicationof the solution to enhance penetration.

When a plurality of wood preservatives are employed, the depth ofpenetration of each may be to a different level, but, in general, wouldbe enhanced as compared with introduction of the wood preservativeswithout the combination of the buffering agent and amine oxide present.

It is an object of the present invention to provide an improved methodfor enhancing depth of penetration into wood of wood preservatives.

It is another object of the present invention to provide such a methodwhich does not require the use of pressure impregnation, vacuum systemsor undesirable, volatile materials.

It is another object of the present invention to eliminate the redryingstep required in prior art pressure and vacuum methods wherein water ora solvent carried the preservatives.

It is yet another object of the invention to provide such a method whichcan be employed on “green” lumber, i.e. lumber which contains undriedsap or other green wood-based products in order to enhance penetration.

It is yet another object of the present invention to provide such amethod wherein the wood to which the solution of the present inventionhas been applied may be stored for a significant period of time prior toa further activation stage.

It is a further object of the present invention to provide a solutionfor use in the method of the invention or a concentrate containing someor all of the desired compounds which can be diluted to create thedesired solution with or without the addition of other compoundsemployable in the method.

It is yet another object of the present invention to provide such amethod which effects rapid penetration of the wood preservatives intothe wood.

It is another object of the invention to provide such a method whichinvolves heating at least one of (a) the wood prior to treatment, (b)the solution and (c) the treated wood.

It is another object of the present invention to provide such a methodwhich is usable on a wide variety of types of wood and resists undesiredgrain raising.

It is yet another object of the present invention to employ a bufferingagent in an amount effective for the desired buffering, but preferablynot in the higher amount needed for the buffering agent to function as apreservative.

These and other objects of the invention will be more fully understoodfrom the following description of the invention on reference to theillustration appended hereto.

BRIEF DESCRIPTION OF THE DRAWINGS

The FIGURE is a schematic illustration of a cross-section of a portionof a wood sample.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

As employed herein, the term “buffering agent” means boric acid, borax,disodium octaborate, phosphates, calcium phosphates, calcium hydroxide,as well as other effective buffering materials and combinations thereof.

As employed herein, “wood” means wood, wood-based materials, wood fibermaterials, forest products, timber, lumber, engineered wood, millwork,joinery, wood laminates, laminated veneer lumber, plywood, laminatedstrand lumber, wood fiber composites, medium density fiberboard,particle board, hard board, oriented strand board, wood fiber resincomposites, wood strand resin composites, wood particle resin compositesand other wood and wood fiber-based materials and fabricated andsemi-fabricated items made therefrom

As employed herein, the term “wood preservatives” means organiccompounds, halo-organic compounds, metalo-organic compounds,organo-salts, borates, organophosphates and non-organoboron compoundshaving fungicidal, insecticidal, water-resistant, termite-resisting,decay-resisting, stain-resisting or other wood-protective properties.

As used herein, the term “amine oxide” or “amine oxide compound” refersto those compounds which are formed as reaction products in the reactionof tertiary amines and hydrogen peroxides and are represented by thegeneral formula:

where R₁, R₂ and R₃ are independent and can be a linear, branched,cyclic, aromatic or any combination thereof of saturated or unsaturatedC1 to C20 group and any C2-C20 carbon atom can be replaced with ahetero-atom selected from the group consisting of O, S and N.

Preferred amine oxides are alkyl dimethyl amine oxides such as decyldimethyl amine oxide, lauryl dimethyl amine oxide, isoalkyl dimethylamine oxide, myristyl dimethyl amine oxide, cetyl dimethyl amine oxide,stearyl dimethyl amine oxide and octyl dimethyl amine oxide. Mostpreferred is N-alkyl (C12-C16)-N,N-dimethylamine oxide (ADO).

In a preferred method of the present invention, a solution contains oneor more amine oxides along with a buffering agent and at least one woodpreservative with the solution having a pH of about 5 to 12.4 andpreferably about 7 to 10 and most preferably about 7 to 8.5.

Below a pH of 7, the maximum penetration effectiveness is not achievedand above a pH of 10, the wood properties may be damaged. Natural woodshave a pH in the acid range. For example, oaks, Douglas fir, aspen andpines have pH's in the range of about 4.0 to 5.5.

A wide variety of amine oxides in the context of wood preservation havebeen known. See, for example, U.S. Pat. Nos. 6,340,384; 6,375,727;6,416,789; 5,833,741; 6,527,981; 6,572,788; 6,508,869 and U.S. patentapplication Ser. No. 10/351,021, which became United States PublishedPatent Application 20040248973, now U.S. Pat. No. 7,056,919, thedisclosures of which is expressly incorporated herein by reference.

If desired, the materials may be provided in concentrate form in asolution of a suitable solvent, such as water, with the final solutionto be applied being created by adding additional solvent and mixing thesame in order to minimize shipping and storing of the solvent volumerequired to make up the difference between the concentrate solventvolume and the final solution solvent volume.

The solution preferably contains about 0.11 to 70 weight percent of oneor more amine oxides and most preferably about 1 to 20 weight percent.The buffering agent is present in about 3 to 80 weight percent andpreferably about 5 to 30 weight percent, all based on weight of totalsolution. The wood preservative is present in about 3 ppm to 50 weightpercent based on weight of total solution and preferably about 20 ppm to5,000 ppm. The solution is in water or another suitable solvent such asethanol or ethylene glycol, for example.

The materials may be provided in the form of a concentrate which will bediluted prior to application to achieve the foregoing relationships.

The solution is applied to the wood by any desired means such asspraying, rolling on or dipping, for example. If desired, amounts ofpressure or vacuum without totally filling the wood with liquid could beemployed. The wood so treated may be stored for a period of time beforeactivation or may be activated promptly thereafter by treatment at anelevated temperature in a high relative humidity environment.Application may be achieved at any temperature between ambient andboiling temperature, but in the preferred approach to the invention, theapplication will be achieved at a temperature of about 30 to 75° C. andpreferably at a temperature of about 50 to 60° C. Activation ispreferably achieved over a period of at least 8 hours at ambienttemperature to steam temperature and preferably at about 70 to 95° C.and at a relative humidity of about 60 to 100% and preferably about 80to 100%. It is preferred to preheat the wood to about 8° C. to 230° C.and most preferably at about 12° C. to 100° C.

In one preferred embodiment, the buffering agent may comprise about 50to 60 weight percent borax and about 40 to 50 weight percent boric acid.

It will be appreciated that more than one buffering agent, amine oxideor wood preservative may be employed and the ranges set forth hereinrefer to each category with a single compound or a combination ofcompounds.

The balance of the solution may be a suitable solvent such as water,ethanol or ethylene glycol, for example, or any desired additives suchas water repellants, waxes, such as paraffin wax, for example, polymers,silicones and combinations thereof. A suitable wax-polymer emulsion isthat sold under the trademark WRS-3 by Kop-Coat, Inc.

If desired, a suitable coloring agent such as an iron oxide pigmentdispersion, red dye or phantom blue dye as offered under the tradedesignation Day Glo or others may be employed.

If desired, glycols and other additives which help solubilize materialssuch as the buffering agent, amine oxides, wood preservatives, waterrepellants and the like may be employed.

Also, additives such as glycols and alcohols which serve as solvents andmay be employed in quantities of about 5 to 40 weight percent based ontotal solution. Among the suitable glycols are ethylene glycol,propylene glycol or polyethylene glycol.

The process has been found to provide deeper and more rapid penetrationthan processes which do not employ a solution as disclosed hereinabove.Enhanced performance is achieved by applying heat to the wood before orafter application or to the solution or by combinations thereof. Thesolution also may be applied without requiring prior art pressureimpregnation or the use of vacuum conditions or undesirable, potentiallyhealth-hazardous and environmentally undesirable volatile solvents suchas petroleum distillates.

Among the wood preservatives usable in the present invention are3-iodo-2-propynyl butyl carbamate (IPBC), diiodomethyl-p-tolylsulfone(DIMPTS), halogenated organics, azoles, quaternary ammonium compounds,isothiazalones, metallic organics, borates, copper naphthenate, copperoxide, tributyltin oxide, zinc omadine, salts of organics andmetallorganics. The amount of these wood preservatives to be employedwill be well known to those skilled in the art with the two additionalcompounds of the present invention expediting the rate of penetrationinto the wood. Within this group, insecticides such as syntheticpyrethroids, nicotinimides, organophosphates, phenylpyrazoles andothers, for example, may be employed. Among the suitable insecticidesare at least one material selected from the group consisting ofnicotinimides, synthetic pyrethroids, borates and combinations thereof.Those skilled in the art will know the conventional quantities of theinsecticides which may be employed.

Fungicides such as chlorothalonil, 2-(thiocyanomethylthio)benzothiazole(TCMTB), methylene bisthiocyanate, bethoxazins, DIMPTS(diiodomethyl-p-tolylsulfone), IPBC (3-iodo-2-propynyl butyl carbamate),triazoles, borates, isothiazalones, phenols, quaternary ammoniumcompounds and combinations thereof and others, for example, may beemployed. Those skilled in the art will know well the conventionalquantities of fungicides to be introduced into the wood.

It will be appreciated that when a plurality of wood preservatives areemployed in the process of the present invention, differentpreservatives may penetrate to different depths of the wood than others.Also, depending upon the wood and its inherent wood pH and othercharacteristics of a specific wood and target penetration, it may bedesirable within the range to modify the pH of the solution.

In another approach to the invention, the wood to which the solution hasbeen applied may be stacked and penetration attained by wrapping thewarm, freshly coated sub-straight stacks in an air-impervious materialsuch as a suitable resinous plastic sheet and allowing it to stand atambient temperature for 8 hours to three days. Additional penetrationmay be achieved thereafter through the activation process.

Another benefit of the present invention is that the wood surfaceappears to be clean and dry with no substantial undesirable grainraising.

The method of the present invention may be practiced in an in-linemanner to process the wood efficiently while avoiding undesired forcessuch as would exist in pressurized treatment which may cause a straightboard to depart from its desired straight configuration.

The wood may also be engineered wood or laminated wood having a gluedlayer or substantial amount of glue therein with the method effectingpenetration of the wood preservative through the glue.

The method may be performed on wood with any amount of moisture contentincluding green (wet) wood and on wood which has moisture at a levelwhich does not exceed the fiber saturation point of the wood and on drywood.

EXAMPLES

In order to provide an enhanced understanding of the invention, exampleswill be provided.

Example 1

Chemical component mixtures as shown in Table 1 were heated to 60° C.using an in-line recirculating heater. The hot mixtures were stirreduntil homogenous. Radiata Pine lumber of dimensions approximately 45 mmdeep, 90 mm wide and 3,000 mm long were immersed for 1 second in one ofthe hot mixtures. Before treatment, the Radiata Pine lumber had oven drymoisture content ranging from 9 to 15% by weight; each piece weighedbetween 4,800 grams and 5,300 grams. The one-second immersion appliedbetween 70 grams and 100 grams of mixture to each piece of lumber. Fivepieces of lumber were immersed in mixtures of 50 to 60° C. The mixtureswere allowed to cool to 30 to 40° C. before a second set of 5 sampleswas immersed. After treatment, the lumber was stored for 6 hours.Different treatment sets were separated during storage. After 6 hours atambient room temperature and humidity, each piece of lumber was storedunder Condition #1 shown in Table 1, while the other half was storedunder Condition #2 shown in Table 2. After 24 hours of exposure toeither Condition #1 or #2, the samples were cut and tested for the depthof penetration using the New Zealand Standard Curcumin test. The resultsof the tests (Table 3) show the unusually deep penetration of mixturesthat contain a buffer and an amine oxide. In this case, the buffer, aboron compound, is also known to have rot and decay inhibitingproperties. In general, an average wood sample penetration in percentdepth at 75 or above would provide the desired inhibition properties.For example, Mixture III in the column for “Storage Condition 2” at bothtemperature ranges A and B produces successful penetration. Consideringthe Compositions III and V as compared with Composition IV, it will beappreciated that the amine oxide and boric buffer quantities wereidentical with a prime difference being that in IV, glycol provided 40%of the total of 58% solvent confirming the use of glycol as a solventand not for another purpose. Considering Table 3, it will be seen thatthe results for Composition IV wherein glycol substituted for asignificant portion of the water as the solvent, the results were not asgood as Compositions III and V. Analytical confirmation using the NewZealand Standard Extraction and Titration Method (Table 4) shows thecorrelation with the Curcumin test results. In this case, the buffer, aborate compound, has penetrated to the center zone of the lumber. Theanalyses also confirmed that the boron compounds were present in thecenter zone at concentrations known to provide inhibition of decay androt fungi. In the column labeled “Detectable Boron”, the word “No”indicates that boron concentration within the zone of 66 to 100%penetration to the center of the wooded sample did not exceed 0.01% byweight. If the word “Yes” appears adjacent a mixture in that column, itmeans that the boron concentration did exceed 0.01% by weight and waspresent in sufficient quantities to inhibit rot/decay. Treated lumbersamples were also stored for 7 months in a plastic bag. During storage,mold grew on the cross-sectional surfaces of all samples. Thepercentages contained in the last column of Table 5 refer to the percentof the exposed cross-sectional area of the sample. This will generallyrelate to depth so that a “0” in this column means that thecross-sectional—exposed end of the sample was 100% covered in mold andthe number “50” means that 50% of the sample was covered with mold. Thesamples treated with the mixture containing fungicides in combinationwith the buffered amine oxide showed surprising mold resistance to adepth of 50% of the depth to the center (Table 5). This result confirmsthat at least one of the fungicides was also carried unusually deep intothe wood by the buffered amine oxide mixture.

The results in Tables 3, 4 and 5 also show the unexpected extremepenetration benefit of heating the buffered amine oxide mixtures and/orheating the buffered amine oxide-treated wood while maintaining highrelative humidity.

TABLE 1 Mixtures Proportions Mixtures Component - Percent by Weight - IWater 60.00 Borate Buffer 40.00 II Water 20.00 Borate Buffer 40.00Glycol 40.00 III Water 58.00 Amine Oxide 2.00 Borate Buffer 40.00 IVWater 18.00 Amine Oxide 2.00 Borate Buffer 40.00 Glycol 40.00 V Water53.00 Amine Oxide 2.00 Borate Buffer 40.00 Water Repellent 5.00 VI Water33.00 Amine Oxide 2.00 Borate Buffer 40.00 Glycol 20.00 Water Repellent5.00 VII Water 56.00 Amine Oxide 2.00 Borate Buffer 40.00 Fungicide(IPBC) 0.15 Fungicide (DDAC) 1.30 Fungicide Cosolvent 0.55 VIII Water58.00 Borate Buffer 40.00 Fungicide (IPBC) 0.15 Fungicide (DDAC) 1.30Fungicide Cosolvent 0.55 Note: Buffer Borate = Disodium OctaborateTetrahydrate Glycol = Propylene Glycol Amine Oxide = N-Alkyl (C₁₂-C₁₆)dimethyl amine oxide Water Repellent = WRS-3 ™ Breathable BarrierFungicide (IPBC)/DDAC/Cosolvents = NP-1 ® Sapstain Control Product

TABLE 2 Treated Wood Storage Conditions 24-Hour Storage RelativeHumidity Temperature Condition* - % - - C. ° - I 65 to 80 18 to 25 II 95to 100 80 to 98 Note: *All samples were stored for 6 hours aftertreatment before 24-hour storage conditions were started.

TABLE 3 Penetration of Wood Average Wood Sample Penetration* in PercentDepth Mixture Storage Condition Temperature 1 2 Mixture - C. ° - - % - -% - I A. 30 to 40° C. 10 15 B. 50 to 60° C. 15 20 II A. 30 to 40° C. 2025 B. 50 to 60° C. 25 25 III A. 30 to 40° C. 25 75 B. 50 to 60° C. 50100 IV A. 30 to 40° C. 20 40 B. 50 to 60° C. 40 70 V A. 30 to 40° C. 3080 B. 50 to 60° C. 55 100 VI A. 30 to 40° C. 30 80 B. 50 to 60° C. 55100 VII A. 30 to 40° C. 25 80 B. 50 to 60° C. 55 100 VIII B. 50 to 60°C. 15 20 *Average of 5 Samples: Depth of penetration determined usingNew Zealand Standard Curcumin indicator for boron. Penetration measuredin the center of the 43 to 45-mm thick sample (100% penetration is 22 mmto reach the center).

TABLE 4 Analyses to Confirm Penetration to Rot/Decay Inhibition LevelsTreated Wood Samples Detectable Boron* Mixture From Depth Zone MixtureTemperatures Storage Condition 66% to 100% I A 1 No I A 2 No I B 1 No IB 2 No II B 2 No III A 2 Yes III B 2 Yes IV B 2 Yes V A 2 Yes VI A 2 YesVII A 2 Yes VIII B 2 No *Boron as (BAE) greater than or equal to 0.01%by weight as determined by New Zealand Standards Titration analysis.Note: 0.01% BAE is recognized as the minimum inhibiting concentrationrequired to inhibit rot/decay spore germination and/or growth instandard tests.

TABLE 5 Penetration of Mold Inhibitor Fungicides Treated Wood SamplesAverage Mold Mixture Inhibition * Mixture Temperature Storage ConditionPercent Depth I A 1 0 I A 2 0 I B 1 0 I B 2 0 II B 2 0 III A 2 0 III B 20 IV B 2 0 V A 2 0 VI A 2 0 VII A 2 50 VIII B 2 5 * Average of 5samples. Treated Radiata Pine samples stored at ambient temperatures 1to 29° C. and 65 to 100% RH in a plastic bag for 7 months.

Example 2

The chemical component mixtures shown in Table 1 were stirred untilhomogenous. The temperature of the mixture was 30° C. Aspen and SouthernYellow Pine-oriented Strand Board (OSB) with commercial specificationsof “ 7/16-inch thickness” heated to 120° to 140° C. was sprayed with thechemical component mixtures. Additional ambient temperature OSB was alsosprayed. The spray applied between 30 and 35 grams of mixture per 1,000square centimeters of OSB. After the spray was applied, the OSB wasstacked. The stacks gradually cooled to room temperature after 24 hours.The OSB board was cut into three depth zones according to FIGURE. Eachcut face was tested for the presence of borate buffer using the standardcurcumin test. Samples of zones that tested positive for borate bufferwere grouped up in a Wylie mill. Ground sample was analyzed for iodineto determine the concentration of IPBC fungicide using an x-rayfluorescence spectrometer. Ground sample was also extracted and thenanalyzed for nicotinimide insecticide using high pressure liquidchromatography. Additional ground sample was digested and then analyzedfor boron to determine the concentration of borate buffer using aninductively coupled plasma spectrometer. The results of the analyses areshown in Table 7 with reference to the FIGURE. The results show theunexpected penetration of the borate buffer as well as the organicinsecticide (nicotinimides) and the fungicide (IPBC).

The study was duplicated. The results are also shown in Table 7. Theduplicate study included two types of nicotinimides. Both nicotinimidespenetrated with the buffered amine oxide mixture.

Referring to the FIGURE, there is represented in fragmentary fashion a7/16-inch wood specimen with the zones delineated with the numbers 1, 2and 3 with increasing numbers referring to regions closer to the centerof the wood specimen.

The study was repeated again; this time, the Disodium Octaborate bufferwas replaced with a mixture of sodium borate pentahydrate and the boricacid in a ratio of 1.17:1.00. In addition, this study included a mixturewith about 40% less buffer (on a BAE basis) and about 80% less amineoxide. (See Table 6, Mixture V.) The results show greatly enhancedpenetration. Also, the mixture was heated to 60° C. and the mixture wasapplied in a commercial OSB plant manufacturing Southern Yellow PineOSB. The OSB was 120° to 140° C. hot from the OSB manufacturing process.The mixture was applied by in process, in-line spray to apply 7 gallonsper thousand square feet of 7/16-inch OSB board. Results of thepenetration tests are shown in Table 7. Results show greatly enhancedpenetration. The treated Southern Yellow Pine OSB was exposed tostandard Formosan termite and fungal tests. Preservative performance wascompared to untreated and 100%-treated controls to determine relativeperformance.

The borate buffer provided some inherent termite and decay resistance.Mixtures with the amine oxide, however, provided much greaterperformance due to enhanced penetration. Mixtures with the bufferedamine oxide with insecticides provided the best performance due to thepenetration of the insecticides. Analyses (ICP method) showed thatborate levels in Zone 3 were as high as 0.34% per weight on a BAE basis.Published historical data shows that Zone 3 would need to contain 0.75to 1.15% BAE to prevent termite feeding in that zone.

It can be concluded that the penetration of insecticides extend to Zone3 even though analyses can only confirm penetration to Zone 2.

It should also be noted that the termite attack centered on Zone 3 inall cases where attacks occurred. This further shows the enhancedpenetration of the borate and insecticide in the buffered amine oxidemixture.

TABLE 6 Mixture Proportions Mixtures Component - Percent by Weight - IWater 97.47 Amine Oxide 0.60 Fungicide (IPBC) 0.18 Fungicide (IST) 0.01Cosolvent for Fungicides 0.74 Surfactant 1.00 II Water 80.00 BorateBuffer A* 20.00 III Water 79.40 Borate Buffer A* 20.00 Amine Oxide 0.60IV Water 77.54 Borate Buffer A* 20.00 Amine Oxide 0.60 Fungicide (IPBC)0.18 Fungicide (IST) 0.01 Insecticide (Nicotinimide) 0.01 Insecticide(Synthetic Pyrethroid) 0.02 Cosolvent for Fungicide 0.64 Surfactant 1.00V Water 83.82 Borate Buffer B 8.30 Borate Buffer C 7.08 Amine Oxide 0.11Fungicide (IPBC) 0.03 Fungicide (IST) <.01 Insecticide (Nicotinimide)0.03 Insecticide (Synthetic Pyrethroid) 0.01 Cosolvent for Fungicides0.39 Surfactant 0.22 *Borate Buffer A = Disodium Octaborate (23.4% BAE)*Borate Buffer B = Sodium Borate Pentahydrate (7.06% BAE) *Borate BufferC = Boric Acid (7.08% BAE) **B + C = 14.16% BAE

TABLE 7 Results of Wood Penetration Analysis Biological Test ResultsAnalytical Percent Protection⁽³⁾ Board Mixture Penetration Formosan RotsBiological Protection Mixture Condition Component Analyses⁽¹⁾ ZoneTermites⁽⁴⁾ Decays⁽⁵⁾ vs. Penetration I Hot IPBC X-ray 1 20 Surfacetreatment Fungicide No penetration II Hot Borate Curcumin 1 30 50Surface treatment Some natural diffusion of borate III Hot BorateCurcumin 3 75 100 Deep penetration borate alone sufficient for decay,but insufficient for termites III Ambient Borate Curcumin 2 75 100Penetration sufficient for decay, but insufficient for termites IV HotBorate Curcumin 3 3 100/100 100/100 Penetration of Borate ICP 3 3insecticides sufficient to IPBC X-ray 3 3 provide termite Fungicideprotection Nicotinimide HPLC 2   2⁽²⁾* V Hot/Fresh Borate Curcumin 3 100100 Penetration/Performance ⁽¹⁾Presence confirmed at levels abovebackground for each component and method ⁽²⁾The Duplicate Seriesincluded two separate nicotinimides. ⁽³⁾Percent protection is reportedin comparison to treated and untreated controls. ⁽⁴⁾AWPA Standard Test⁽⁵⁾EN 113 adapted

Referring in Table 7 to the heading entitled “Biological Protection vs.Penetration”, the Mixture I specimen experienced rotting in Zones 2 and3 and termite attack in Zones 1, 2 and 3. The Mixture II showed rot inZone 3 and termite attack in Zone 3.

Mixture III showed no rot and termite attack only in Zone 3. Mixture III(hot condition) showed that Mixture III (ambient condition) showed norot and termite attack in Zones 2 and 3, thereby showing the benefit ofheating of the wood. Mixture IV showed no rot and no termite attack.Mixture V also showed no rot and no termite attack.

Cross-sectional analysis of treated boards showed substantialpenetration of key ingredients, especially the borate component.

From these examples, it can be seen that treatment utilizing thesolutions and process outlined in this invention imparts no significantdiscoloration or grain-raising to treated lumber. Moreover, surfacetreatment following this invention allows for penetration of activeingredients into lumber without the need for pressure or double vacuumtreatments.

It will be appreciated, therefore, that the method of the presentinvention provides an efficient, safe, economically feasible method ofrapidly and effectively causing deep penetration of wood preservativesas a result of the unique solution and the combination of bufferingagent and amine oxide. All of this is accomplished without requiringpressure impregnation, the use of vacuum conditions and the use ofhealth and environmentally undesirable solvents.

Whereas particular embodiments of the invention have been describedherein for purposes of illustration, it will be evident to those skilledin the art that numerous variations of the details may be made withoutdeparting from the invention as set forth in the appended claims.

1. A wood preservative solution comprising at least one amine oxide, atleast one wood preservative and a buffering agent with the balance beingat least one suitable solvent, said solution having a pH of about 7 to10, and said buffering agent being present in a sufficiently smallamount that it does not provide a substantial wood preservation effect,whereby the interaction of the amine oxide with the buffering agent willhave a synergistic effect to effect a greater depth of penetration ofsaid wood preservative.
 2. The solution of claim 1 including employingwater as said solvent.
 3. The solution of claim 1 including said amineoxide being selected from the group of alkyl dimethyl amine oxides,decyl dimethyl amine oxide, lauryl dimethyl amine oxide, isoalkyldimethyl amine oxide, myristyl dimethyl amine oxide, cetyl dimethylamine oxide, stearyl dimethyl amine oxide, octyl dimethyl amine oxideand N-alkyl(C12-C16)-N,N-dimethylamine oxide (ADO) and combinationsthereof.
 4. The solution of claim 1 including employing said bufferingagent in an amount of about 3 to 80 weight percent based on totalsolution weight.
 5. The solution of claim 4 including employing saidamine oxide in an amount of about 0.11 to 70 weight percent based ontotal solution weight.
 6. The solution of claim 5 including employingsaid wood preservative in an amount of about 3 ppm to 50 percent basedon total solution weight.
 7. The solution of claim 5 including employingsaid amine oxide in a weight percent of about 1 to 20 percent of saidsolution.
 8. The solution of claim 1 including employing said bufferingagent in a weight percent of about 5 to 30 percent of said solutionweight.
 9. The solution of claim 1 including employing as said solutiona solution having a pH of about 7 to 8.5.
 10. The solution of claim 1including employing at least one solvent additive in said solution. 11.The solution of claim 10 including said solvent additive selected fromthe group consisting of glycols, alcohols and combinations thereof. 12.The solution of claim 10 including a water repellent being present as asaid additive.
 13. The solution of claim 12 including said waterrepellent including a wax-polymer emulsion.
 14. The solution of claim 1including said wood preservative being present in amount of about 20 ppmto 5000 ppm.
 15. The solution of claim 14 including said woodpreservative including at least one fungicide.
 16. The solution of claim15 including said fungicide selected from the group consisting of3-iodo-2-propynyl butyl carbamate, diiodomethyl-p-tolylsulfone,triazoles, isothiazalones, phenols, quaternary ammonium compounds andcombinations thereof.
 17. The solution of claim 14 including said woodpreservatives including at least one insecticide.
 18. The solution ofclaim 17 including said insecticide including at least one materialselected from the group consisting of nicotinimides, pyrethroids andcombinations thereof.
 19. The solution of claim 1 including said woodbeing a wood selected from the group consisting of engineered wood andlaminated wood having a glued layer or substantial amount of gluetherein.
 20. A wood preservative solution comprising at least one amineoxide, at least one wood preservative and a buffering agent with thebalance being at least one suitable solvent, and said buffering agentabout 50 to 60 weight percent borax and about 40 to 50 weight percentboric acid.